HB-Line Phase II process requires the addition of sodium permanganate followed by a sodium nitrite addition to prevent the precipitation of plutonium solids in a non-geometrically safe vessel. Previous experimental work has shown this method effective. Current concerns are related to the gas generated by the reaction. Potential difficulties include tank over-pressurization and tank overflow due to foaming or eructation. It is also necessary to verify that the quantity of permanganate specified

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... y the facility is sufficient to reach the desired endpoint in a single addition. Several experiments were performed in which sodium permanganate and sodium nitrite were added to simulated, non-radioactive filtrate solutions at constant feed rates. The volume of gas generated by the reaction was monitored. Experiments were also performed using a "reverse addition" method. In this method the permanganate was added to the reaction vessel first, then the simulated filtrate solution was added to the vessel at a constant rate. It was found that the gas generation rate is not a linear function of the permanganate feed rate. The gas generation rate peaked early during the permanganate addition for all of the standard addition experimental runs. The peak gas generation rate was found to be strongly dependent on the permanganate feed rate. No significant foaming or bubbling occurred at the feed rates tested. Many technical issues make the "reverse addition" method an undesirable option. Problems associated with this method include excessive solids generation, increased NO x generation, and excessive gas generation. Experimental results indicate the amounts of permanganate supplied as input by the facility are not sufficient to reach the desired endpoint.